use std::path::PathBuf;

#[derive(Clone)]
pub struct NixStorePath {
    pub hash: String,
    pub name: String,
}

impl NixStorePath {
    pub fn from_str_symlink(path: &str) -> Result<Self, String> {
        Ok(Self::from_path_buf_symlink(PathBuf::from(path))?)
    }

    pub fn from_path_buf_symlink(path: PathBuf) -> Result<Self, String> {
        Ok(Self::from_path_buf(path.read_link().map_err(|err| err.to_string())?)?)
    }

    pub fn from_path_buf(path: PathBuf) -> Result<Self, String> {
        let store_path_name = path.iter().nth(3)
            .ok_or_else(|| String::from("Can't read store path name"))?
            .to_str()
            .ok_or_else(|| String::from("Failed converting store path name to string"))?
            .to_string();
        Ok(Self::from_store_path_name(store_path_name)?)
    }

    pub fn from_store_path_name(store_path_name: String) -> Result<Self, String> {
        let (hash, name) = store_path_name
            .split_once("-")
            .ok_or_else(|| String::from("Failed splitting store path name for hash and name"))?;
        Ok(Self {
            hash: hash.to_string(),
            name: name.to_string(),
        })
    }

    pub fn to_prometheus_metric(self, infix: String) -> Result<String, String> {
        return Ok(format!("nixos_{}_hash{{hash=\"{}\"}} 1\nnixos_{}_name{{name=\"{}\"}} 1\n", infix, self.hash, infix, self.name));
    }
}